Pre-moistened, skin cleansing tissues are well known commercially and are referred to as wet wipes, towelettes, and the like. These tissues may be prepared from paper or paper products which are treated in such a manner so as to improve their wet strength. Such tissues are generally sized such that they are useful for use as a wash cloth, and may be packaged in closed containers. Alternatively, the tissues may be individually packaged.
Wet wipe tissues are generally treated with an aqueous alcohol solution in order to maintain moistness. The tissues may also comprise a surface active detergent, humectant, and a scenting agent or fragrance.
Numerous wet wipe like materials have been described. U.S. Pat. No. 3,808,165 describes a process for preparing a wet wipe in which boric acid is added to polyvinyl alcohol (PVOH) rather than adding the boric acid to the lotion at a later time. The web is dried, the heat of drying breaking down the organic acids present which raises the pH to stabilize the binder. Sodium bicarbonate is not used to raise the pH.
U.S. Pat. No. 3,881,210 describes a sanitary wiper comprising a PVOH central layer, wherein the multilayered structure is bonded together by means of embossing roll with a land area of 4 to 25%. However, no stabilizing ingredients, percentages, nor strength criteria are specified.
U.S. Pat. No. 4,309,469 describes a wipe which is bonded with a three part adhesive binder consisting of PVOH and a self-crosslinking thermosetting polymer and a non-self-crosslinking thermosetting polymer. The complexing agent is alpha hydroxy and O-aromatic hydroxy acids rather than boric acid and sodium bicarbonate.
U.S. Pat. No. 4,343,133 describes a polyvinyl acetate latex impregnated towelette, which uses a high percentage of boric acid, at least 3%, which is much too harsh for many applications. This towelette also does not comprise sodium bicarbonate.
U.S. Pat. No. 5,256,417 describes a water dispersible towelette which is impregnated with non-aqueous lotion formulations. The non-aqueous lotion composition of organic compound stabilizes the PVOH binder but does not dissolve PVOH.
U.S. Pat. No. 3,689,314 uses a different process to prepare flushable wrappers for absorbent pads. The PVOH binder and the chemical additives are added together and dried. Heat causes the chemicals to react and render the binder sufficiently strong in the condition of use. The environment of the absorbent pad is a very small zone exposure of low level of saturation of the body fluids. The time of exposure is also limited to a few hours, rather than months. In addition, heating is required for crosslinking after the borax is formed. Furthermore, less than 0.5% sodium bicarbonate is used.
A major concern of many of these existing tissues, which use a flushable binder system containing boric acid, is that boric acid in high dosage can cause toxic skin irritation, particularly in individuals with compromised skin. Thus, there is a need to provide a gentle lotion system containing low concentrations of boric acid. In addition, all of the wet wipes currently in the marketplace have an acidic pH. The most common range is from a pH of 4.0 to 5.5. The skin's pH is about 5.5 in adults and babies, which is the pH most manufacturers try to achieve when developing pH-balanced products.
U.S. Pat. No. 5,252,332 describes a premoistened, flushable towelette impregnated with polyvinyl alcohol-containing binders. A PVOH based binder is applied to the non-woven web, which is lotionized with a lotion containing boric acid and sodium bicarbonate. The sodium bicarbonate range is stated to be 0.2 to 3%. In addition, the towelette contains an undesirably high quantity of boric acid. The borate to bicarbonate ratio is 4:1 to 1:4, and is preferably 2:1 to 1:2. Moreover, the towelette is susceptible to growth of microorganisms, especially mold, and is therefore not appropriate for long-term storage. In contrast, Applicants' invention provides a borate to bicarbonate ratio of 1:8.5 to 1:12 and provides a far superior wet strength.
Applicants' invention provides a number of features which are desired but not found in the prior art. First, Applicants' invention provides unexpected higher wet strength that are unavailable in other formulations with similar needs. Second, it provides for a high percentage of sodium bicarbonate which enhances cleansing and deodorizing, while providing an alkaline pH suitable for babies and infants. Finally, Applicants' invention is surprisingly compatible with existing BABY FRESH.TM. lotion system, synergistically making a gentle and efficacious cleansing wipe which is also flushable, dispersible and biodegradable. Applicants' invention provides for the first lotionized wet wipe having an alkaline pH, high wet strength, low boric acid concentrations that provide mildness, and a preservative system providing for long-term storage. Moreover, Applicants' invention surprisingly provides a wet wipe having an alkaline pH while simultaneously being mild and gentle.
The present invention provides a personal care, pre-moistened, cleansing wet wipe comprising a PVOH containing binder in contact with an aqueous solution containing borate and bicarbonate ions. The towelette exhibits desirable wet tensile strength but rapid disintegration in water. This material is used as a flushable, dispersible and biodegradable wet wipe for babies, kids, teens and adults of both male and female of all ages. Applicants' wet wipe can be disposed discreetly by flushing down the toilet bowl safely. The product also meets aerobic and anaerobic biodegradation existing in sewer and septic systems. Applicants' invention further comprises a mild binder and lotion system that allows the wet wipe to disperse into very small fibrous components under conditions of volumes and velocity of the water in which the wipe is placed.